Mechanism to be mounted between two parts, whose mutual distance must be variable

ABSTRACT

A mechanism is described for mounting between two parts, such that the mutual distance between the parts may be varied. The mechanism includes a bar pivotally journalled in a bearing at one end and interconnected to an actuating device. The actuating device is pivotally suspended to one of the structures at one end and is connected to the bar at the other end. The pivot axis of the bearing extends obliquely to a plane containing the suspension point of the actuator and the point of connection between the actuator and the bar.

The invention relates to a mechanism to be mounted between two parts,whose mutual distance must be variable, preferably against a load, e.g.the bottom and the frame of a bed, which mechanism has a bar pivotallyjournalled and connected with one of the parts at its one end, the barbeing at its other end which acts upon e.g. is in rest with, the otherpart, or between its ends coupled with a pivotally suspended drivingmeans of the elongation or extension type.

The last mentioned end of the bar can, for example, bear against and acton the under side of a load surface, e.g. a goods platform or the bottomof a bed, or on the upper side of a pressure plate, e.g. on the chassisof a goods platform or on the frame of a bed. On the actuation of thebar by the driving means the bar will turn in its bearing and with theend situated opposite the bearing it will press the surface againstwhich it bears away from the bearing, e.g. upwards.

If the said bar, which in the above-mentioned example acts as a liftingbar in such mechanism, is journalled at one end like a hinge and at adistance therefrom or at its other end is connected with a driving meansoperative and situated in the longitudinal direction of the bar, only avery poor ratio can be obtained between the greatest lift and theminimum height of the mechanism, because the perpendicular component ofthe power of the driving means and thereby the lifting force becomesvery poor or completely disappears if the bar is lowered towards or to ahorizontal position on a level with the driving means. Such mechanisminclusive of the driving means will also have a relatively great totallength.

The purpose of the invention is to produce a mechanism, especially alifting mechanism, which has an extremely small height in the initialposition, and which has also small dimensions in the longitudinal andlatitudinal directions, at the same time permitting a powerful lift,also from a horizontal initial position.

In view of this, a mechanism of the kind dealt with above ischaracterized in that the driving means actuates the bar mainlytransverse to its longitudinal direction, and in that the axis of thebearing of the bar extends obliquely in relation to a plane containingthe connecting line between the suspension point of the driving meansand its point of application on the bar.

As a result of the oblique bearing of the one end of the bar, thedriving means when actuating the bar will always make the latter turn inits bearing, the opposite end of the bar describing a circular arc withits centre in the axis of the bearing. This also applies even though inthe initial position the bar is on a level with the driving means,thereby permitting the very low height.

The lifting capability expressed as the relationship between the liftingmovement and the travel of the driving means, particularly the extensionof the driving means, depends partly on the angularity of the axis ofthe bearing.

In an embodiment of the mechanism according to the invention in whichthe axis of the bearing follows the direction of a spatial diagonal inan equilateral cube having the bar as a lateral edge and having thedriving means extending along a lateral edge at a right angle thereto ona level with the bar in the initial position, the maximum liftingmovement, during which the bar is moved from a horizontal to aperpendicular position, will with a suitable mounting of the drivingmeans result in an elongation of this to √3 times the lifting movement,that is, an elongation by approx. 73%, as will be made more explicitbelow.

A mechanism according to the invention has a multitude of possibleapplications. By virtue of its short height, it can as stated be mountedbetween the frame and the bottom of a bed and serve as a bed lift,particularly in a sickbed, but it can for example also be used to liftgoods and other material for transport, e.g. on a goods platform, fromground level to loading height at the platform of a truck such as alorry or van or a goods waggon. Also by mutual displacement between twoparts on non-perpendicular planes, e.g. on a horizontal plane, can amechanism according to the invention be used analogously, e.g. toactuate machine parts to sideways displacement against an elastic force.

Further details of the invention are given below partly on the basis ofa skeleton diagram in FIG. 1 and two schematic presentations of alifting mechanism in FIGS. 2 and 3.

FIG. 4 is a graphic presentation of the lifting movement as a functionof the elongation of the driving means.

In FIG. 1 the actuating or lifting bar 1 is shown schematically withfull-drawn lines in the lowered initial position. At one end the bar 1is pivotally journalled with a bent end part in a tilted bearing 2 inthe form of a short pipe section, and at its opposite end the bar 1 isconnected via an universal joint 5 with a driving means 3 in the form ofan extension or elongation motor, which is shown by full-drawn lines inthe likewise horizontal initial position. At the end situated oppositethe point of connection with the bar 1, the extension motor is pivotallysuspended in another universal joint 4.

By an extension or elongation motor is here meant a motor which onactivation from the initial position shown by full-drawn lines increasesits length, as shown by dotted lines on the drawing, e.g. by a spindle 8being pushed out of the motor housing by mechanical, hydraulic orpneumatic means.

In the embodiment shown by way of example the bar 1 in the initialposition forms a lateral edge in an imaginary equilateral cube, and thedriving means 3 forms or lies along another side edge at a right anglethereto and in the same horizontal plane. The axis direction of thebearing 2 follows the direction of a spatial diagonal in the cube asindicated by a double dot-and-dash line Z, i.e. the bearing 2 could asregards function analogously lie on the extension of the diagonal beyondthe cube.

When the driving means 3 is activated from the position shown byfull-drawn lines, it actuates the bar 1 to turn in the bearing 2, andthe free bar end positioned opposite the bearing 2 will describe acircular arc with the bearing 2 as the centre. Owing to the tiltedbearing 2 the projection of the orbit of rotation on a plane containingthe perpendicular lateral face of the cube, whose bottom limitation isformed by the bar 1, or on a plane at right angles thereto, will be anellipse as indicated in the sketch. For the actual lifting movement thepart of the ellipse is used which is drawn with a full-drawn line andwhich corresponds to a circular arc of 120° in the shown example.

The mechanism according to the invention is notable in that the bar 1and the motor 3 in the horizontal initial position lie substantially inthe same plane, which gives the mechanism an extremely low height in theinitial position. Still, despite this position of the lifting bar anddriving means, the latter, as a result of the tilted bearing 2, is ableto move the bar 1 out of the initial position and along theabove-mentioned orbit to the end position shown by dotted lines. Thefact that this is possible has to do with the first part of the movementfrom the initial position having a considerably horizontal component inrelation to the perpendicular component, which on the other hand laterpredominates, as also appears from the sketch.

If the length of the bar 1 in FIG. 1 and thereby the edge length of theimaginary cube is designated by a, the lifting height will also be a,and in the end position the motor 3 will be extended to a √3, namely√a² + (a² + a²), i.e. an extension of approx. 73%.

In a practical lifting mechanism, shown in FIG. 2, and in which thetubular bearing 2 in FIG. 1 is replaced by an axle journal taking acorresponding course, which is attached to a frame 7 bearing themechanism and indicated merely by dot-and-dash lines, and whichcooperates with a bore in the bar 1, the free end of the lifting bar 1is in rest with the under side of a lifting surface 6, likewiseindicated with dot-and-dash lines, which can for instance serve to takeup goods or materials to be lifted up to a certain height, e.g. with aview to transferring them to the platform of a lorry, or which cananalagously be a pressure plate on the lower side of the bottom of abed, which must be able to be lifted.

The bar 1 bears against the lifting surface 6 with a slide bearing,which during the movement of the bar from the position shown byfull-drawn lines to the one shown by dotted lines in FIG. 2 moves underthis lifting surface, thereby pressing it upwards. The bar end or theslide bearing, respectively, thereby follow an orbit on the under sideof the lifting surface which forms part of an ellipse.

The bar end can in a manner not shown be formed like a metal ball, whichslides against a metal sheet on the under side of the lifting surface indirect rest against this metal sheet or with an interjacent thrust pador foot of plastic, which with a dome-formed part encircling slightlymore than half of the ball is pivotally mounted on this, and which has aplane surface in rest against said metal sheet. FIG. 2 also shows thatthe motor 3 is connected to the lifting bar 1 a short distance away fromthe latter's free end, which for instance in the manner just describedbears against the under side of the lifting surface 6.

No guide has been shown in FIG. 2 for the lifting surface 6 shown withdot-and-dash lines in the lateral direction, because such guide is not apart of the invention, but the surface 6 can for instance be guided bymeans of any collapsible mechanism, e.g. of the jaw-tongs type.

The relative placing shown in FIG. 1 of the bearing 2, the bar 1, thedriving means 3 and the universal or cardan joints 4 and 5 thus, asstated, serve only as an example which results in a fairly compact andefficient lifting mechanism, but other placings of one or more of thesaid parts, e.g. as shown in FIG. 2, and other angles for the axis ofthe bearing 2 are possible without any alteration in the fundamentalinvention. However, as regards the tilted position of the bearing 2, itshould be noted that under all stages of operation the bearing axis mustbe oblique in relation to or intersect an arbitrary plane containing theline of connection between the point of suspension 4 of the drivingmeans 3 and the the driving means' point of application 5 on the liftingbar 1, such that the direction of the power from the driving means 4never becomes parallel to the direction of the bearing axis. The axis ofthe bearing 2 may expediently extend into a space which is cube-formedand having the bar 1 in the horizontal initial position as an edge on aside which in its plane contains the point of suspension 4 of thedriving means 3, e.g. a cube as shown in FIG. 1 or one of the threeother possible cubes with the bar 1 as lateral edge and with a lateralsurface in a plane containing the point of suspension 4.

It is also possible for the movable part of the driving means 3, thespindle 8, not to be wholly drawn into the motor housing in the initialposition shown in FIG. 1. On continued retraction of the spindle 8, thebar end will continue a short distance downwards along the orbit of theellipse as indicated. This continued movement, which can for instancecorrespond to the movement along a circular arc of 60°, can in certaincases be exploited, e.g. if the lifting mechanism serves as a bed liftand in the course of its main movement lifts and lowers the bottom of abed in relation to its frame. The continued movement of the bar end willthen be able to be exploited for separate lifting and lowering of thebed head as desired by means of a suitable system of rods.

FIG. 3 shows a practical embodiment of a bed lift having two motorscomplete with lift bars. Parts equivalent to those shown in FIGS. 1 and2 bear corresponding reference marks. Of the hindmost mechanism, to theright in FIG. 3, is seen only the motor 3', the remainder of thismechanism being hidden behind other parts.

The motors 3,3' are here pivotally mounted in universal joints 4, onlyone of which is visible, on the under side of a lifting surface 6, whichis here the bottom of a bed. Correspondingly, the lifting bars 1, againonly one of which is visible, are pivotally mounted in bearings 2 on theunder side of the bottom of the bed, and their free ends are in restagainst the bed frame or against a pressure plate (not shown) on the bedframe, which is designated 7, because it corresponds to the stationarypart 7 in FIG. 2.

The motors 3 and 3' can be activated independently of each other in theshown example, so that the bottom 6 of the bed can be made to assumearbitrary oblique positions as desired.

The bottom 6 of the bed can be guided by means of a system of rods whichis adapted according to the purpose in question, in the shown example byrods 9, 10, which co-operate with slide rails 11 on the bed frame 7, andof which the bars 10 are also coupled with the bed frame via a togglejoint 12. As a matter of fact the guidance for the lifting surface, thebottom 6 of the bed, can be formed by skilled persons in accordance witha desired lifting function.

I claim:
 1. Mechanism to be mounted between two parts, whose mutualdistance must be variable, preferably against a load, e.g. the bottomand the frame of a bed, which mechanism has a bar (1) pivotallyjournalled in a bearing (2) and connected with one of the parts of oneend, the bar also being coupled with a pivotally suspended (4) drivingmeans (3,8) wherein the driving means (3,8) actuates the bar (1)substantially transverse to its longitudinal direction, and wherein theaxis of the bearing (2) of the bar (1) extends obliquely in relation toa plane containing the connecting line between a suspension point (4) ofthe driving means (3,8) and its point of application on the bar (1). 2.Mechanism according to claim 1, wherein the axis of the bearing (2)extends into a space which is cube-formed and has the bar (1) as alateral edge.
 3. Mechanism according to claim 1 wherein the axis of thebearing (2) follows the direction of a spatial diagonal in anequilateral cube, having the bar (1) as a lateral edge and having thedriving means extending along a lateral edge at right angles thereto inthe same plane as the bar (1) in the initial position.
 4. Mechanismaccording to claim 1 wherein the driving means (3,8) is coupled to thebar (1) at an end of the bar (1) opposite the bearing (2).
 5. Mechanismaccording to claim 1 wherein the driving means (3,8) is coupled to thebar (1) between the one end and an opposite end.
 6. Mechanism accordingto claim 1 wherein the driving means (3,8) is a pivotally suspendedactuator.